P0174 System Too Lean (Bank 2)
The same as P0171, but for bank 2 on V6 and V8 engines.
Common causes
- Vacuum leak
- Dirty or faulty MAF sensor
- Weak fuel pump or clogged filter
- Faulty bank 2 oxygen sensor
Symptoms
- Rough idle, hesitation – or no symptoms at all
Can I drive with it?
Usually drivable, but get it checked soon.
Tip: Together with P0171, suspect something both banks share: the MAF sensor, a large vacuum leak or low fuel pressure.
Which scanner reads it?
Any OBD2 scanner reads it; live fuel-trim data helps diagnose it.
Budget tools like the ANCEL AD310 read it; tools with live data and graphing – like the BlueDriver or OBDLink MX+ – help you find the cause. Not sure which fits you? Try the Find My Scanner quiz.
In the data
How common is it? At New York’s emissions inspections in 2020–21, P0174 was the #7 code found on cars that failed – 2.0% of all the codes found.
Of the vehicle complaints owners filed with NHTSA from 2015 to 2025, 18 quote P0174 – most often from Chevrolet, Toyota, Buick owners. Complaints lean toward serious problems, so treat this as a sign of how often the code turns up in real reports, not how often cars get it.
Both sources are compared on the Trends page.
Related codes
General information to help you understand a code – not a diagnosis. Your car’s service information or a qualified mechanic has the final word. See how we research.